MI5’s group of skilled surveillance experts are known as the Watcher Service and, working in teams, maintain covert observation on fixed targets, such as diplomatic missions, from permanent posts. They are also deployed against other terrorist and espionage suspects. The members are trained to a high standard and are considered among the most professional in the world. They rarely give evidence in prosecutions so as to avoid compromising their methods, but in September 1988 some were called as witnesses in the inquest conducted after Operation FLAVIUS in Gibraltar.